Among 6,510 HCWs, 550 (8

Among 6,510 HCWs, 550 (8.4%) in the study had a positive PCR result for SARS-COV-2. When analyzed by serostatus at baseline, 519 (8.4%) of 6,194 seronegative participants had a positive PCR after serology screening, representing a SARS-CoV-2 illness rate of 4.25 per 10,000 days at risk (95% CI, 3.89C4.63) (Fig.?1, panel A). serostatus only, 519 (8.4%) of 6,194 baseline seronegative participants had a positive PCR after baseline serology screening (4.25 per 10,000 person days). Of 316 participants who have been seropositive at baseline, 8 (2.5%) met criteria for possible SARS-CoV-2 reinfection (ie, PCR positive 90 days after baseline serology) during follow-up, a rate of 1 1.27 per 10,000 days at risk. The adjusted rate ratio for possible reinfection in baseline seropositive compared to illness in baseline seronegative participants was 0.26 (95% confidence interval, Amiloride HCl 0.13C0.53). Conclusions: Seropositivity in HCWs is definitely associated with moderate safety from long term SARS-CoV-2 illness. A recent study in the United Kingdom reported that healthcare workers (HCWs) with serologic evidence of previous natural illness with severe acute respiratory coronavirus disease 2 (SARS-CoV-2) are at an 90% lower risk for coronavirus disease 2019 (COVID-19) over 6-weeks of follow-up.1 In fact, some observations suggest that organic infection may provide related safety to vaccination in preventing long term reinfection.2 However, studies reporting low rates of SARS-CoV-2 illness in seropositive individuals, including HCWs, may not be generalizable to other countries or areas because of different admixtures of SARS-CoV-2 clades, underlying population illness rates, and mitigation plans that may affect exposures related to main illness and reinfection rates. Understanding the risks for reinfection is particularly relevant to US HCWs, who have been at very high risk for COVID-19, with 473,705 instances and 1,559 deaths as of April Amiloride HCl 22, 2021.3 Not only do HCWs have significant risk due to repeated patient-facing exposures and carrying out high-risk procedures, they are also at significant risk for community exposure to SARS-CoV-2.4,5 In addition, although vaccination has been available to HCWs, intentions to get vaccinated vary due to issues over adverse effects of the vaccine and perceived immunity following natural infection. In fact, reports of plans to obtain the vaccine range from 53% to 80%,6 which suggests that a significant portion of HCWs will remain at risk for COVID-19 despite available vaccines. Consequently, predicting SARS-CoV-2 illness rates among unvaccinated HCWs with and without a history of SARS-CoV-2 illness is important as clinicians and general public health officials develop strategies to contain COVID-19 while keeping a sufficient healthcare work force. Here, we describe the 6-month SARS-CoV-2 illness rates in HCWs with and without serologic evidence of prior illness and examine switch in antibody status over time. We hypothesized the following: (1) antibody seroreversion (seropositive to seronegative during follow-up) would be common; GNG7 (2) seropositivity at baseline would be associated with a lower rate of PCR Amiloride HCl positivity for SARS-CoV-2 than observed in baseline seronegative HCWs; and (3) rates of possible reinfection (ie, a PCR-positive result that occurs 90 days after a positive serology result at baseline) observed will be considerably higher than those recently reported in the United Kingdom over 6 months of follow-up.1 Methods Study design and population We conducted a prospective cohort study with HCWs recruited in May and June of 2020 from Northwestern Medicine. Northwestern Medicine is an academic healthcare system comprising 10 private hospitals, 18 immediate-care centers, and 325 outpatient methods in the Amiloride HCl Chicago metropolitan area. The largest hospital in the health system is definitely in downtown Chicago, Amiloride HCl whereas the additional 9 regional centers are in the western, northwestern, and northern suburbs of Chicago. Affiliated outpatient methods and immediate-care centers are in downtown Chicago and the surrounding suburbs. Details of the study and recruitment techniques have been reported previously.4 Briefly, HCWs were invited to participate in a cohort study of SARS-CoV-2 serology and COVID-19 risk and after providing written consent, participants were invited to undergo serology screening between May 26 and July 10 (baseline) and then between November 9 and January 8, 2021 (follow-up). Participants completed a self-report survey at baseline that assessed demographic characteristics, occupational group, participation in specific occupational jobs, symptoms, and community exposure to COVID-19. After the baseline survey, participants were.